Apparatus for backing up a shell



1960 M. J. STROBEL 2,920,360

APPARATUS FOR BACKING UP A SHELL Filed Oct. 5, 1956 3 Sheets-Sheet l ATTORNEYS Jan. 12, 1960 M. J. STROBEL APPARATUS FOR BACKING UP A SHELL 3 Sheets-Sheet 2 Filed Oct. 3, 1956 I INVENTOR. Merry/Z JAY/vial, BY

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Fwd PM A TTORNEYS United States PatentO 2,920,360 APPARATUS FOR BACKING UP A SHELL Merrill J. Strobe], Ocean City, N.J., assignor to Westcott & Thomson, Inc., Philadelphia, Pa., a corporation of Pennsylvania Application October 3, 1956, Serial No. 613,694 6 Claims. (Cl. 22- 58) This invention relates to improvements in apparatus and method for backing up a shell, and more particularly concerns apparatus and method for backing up a copper printing shell to form an electrotype plate or the like.

In conventionally preparing an electrotype plate, a plastic mold is made having protuberances shaped to represent the desired printing matter and then copper is deposited in a thin layer on the mold. When the thin copper layer is stripped ofl the mold it is called a copper shell. This shell cannot be used for printing since it is very thin, bendable and weak. An object of this invention is to back up the shell with lead, or the equivalent, in order to produce a rigid printing plate having a flat and true printing surface.

It has long been desired, and is an object of this invention, to produce an electrotype plate having a printing face that is almost perfectly uniform except for the printing indentations and is free from unwanted indentations and protuberances, and has a back face that is almost perfectly parallel to the printing face. Another object is to substantially eliminate the time-consuming and costly shaving of the back face which has heretofore been necessary to make it parallel to the printing face. It is also desired to produce an electrotype plate that does not require hammering on the back face of the plate to bring up low spots on the printing face, and to eliminate the use of a pressure sensitive coating on the printing face to hold the shell in position in a casting box while the lead backing is being poured.

Other objects and advantages of this invention, including the provision of an apparatus for forming an electrotype plate which is easily operated, which requires a minimum number of operations, and which is rapidly and easily used by the operator, will further become apparent hereinafter and in the drawings in which:

Fig. 1 represents a view in perspective of apparatus for forming an electrotype plate in accordance with one embodiment of this invention;

Fig. 2 represents a plan view of the apparatus on an enlarged scale and with parts broken away in order to illustrate important details;

Fig. 3 represents a sectional view taken as indicated by the arrows III III which appear in Fig. 2;

Fig. 4 represents an enlarged view of the apparatus indicated by the numeral IV which appears in Fig. 2;

Fig. 5 represents an enlarged view in section taken as indicated by the lines and arrows VV which appear in Fig. 4; and

Fig. 6 represents a perspective view in section and partly broken away of one of the components of the apparatus. 7

Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure selected for illustration in the drawings and are not intended to define or limit the scope of the invention.

Turning now to the specific embodiment of the invention selected for illustration in the drawings, the numalloy, and with a layer 35 of lead superimposed upon layer 34. Layer 35 has a back faceand perforations coated with a layer 34 Patented Jan. 12, 1960 her '11 designates generally an apparatus for forming an electrotype plate having an enclosure 12 including a front wall 13, side walls 14 and a top plate 15. Mounted on side wall 14 are on and off buttons 16 which control a vacuum pump motor, and mounted in a recessed portion .17 of front wall 13 are buttons 18 which control solenoid valves to control the vacuum system. Top plate 15 has positioned immediately beneath it a bottom plate 21, and top plate 15 has inscribed, at the right in its upper side, grooves 22 in which are located perforations 23 which extend into the top plate. Similar grooves 22a and perforations 23a are located at the left of plate 15. Positioned at the rear of enclosure 12 is a temperature gauge 24 which indicates and controls the temperature in the plates 15 and 21. Placed on top of plate 15 are a number of magnetic hold-down dams 25, and located between top plate 15 and bottom plate 21 are a series of electrical conducting rods 26 which, when energized, serve to heat the top plate 15.

Referring to Fig' 3, which is a cross sectional view of the upper portion of apparatus 11, the ends of rods 26 are connected to conductors 27 which are connected to an electrical circuit including a source of electrical energy (not shown). Perforations 23, 23a are adapted to evacuate air from the printing face 28 of a copper shell 31 for maintaining the shell in a flattened position against top plate 15. Shell 31, as shown in Fig. 3, has already been formed into an electrotype plate 32 with the non-printing face 33 of shell 31 covered by a layer 34 of bonding material, which is preferably a lead-tin or the equivalent 36 that is parallel to the printing face 28.

A vacuum source (not shown) is connected to perforations 23, through a pipe 37, T connector 38, pipe 41, solenoid valve 42, pipe 43, connector 44 and pipe 45 which is threaded into a flanged insert 46 that is bolted to top and bottom plates 15 and 21. The upper end of insert 46 is provided with a shoulder 47 along its outer periphery in which is inserted a soft metal, preferably copper, ring 48 which maintains a vacuum seal. Pipe 45 is provided with a drain plug 51. The other side of T connector 38 is connected to similar apparatus including pipe 410:, a solenoid valve 42a, a pipe 43a, a connector 44a, pipe 45a having drain plug 51a, insert 46a 23a located in grooves 22a.

As is shown in Fig. 6, magnetic hold-down dams 25 include a body member 52 having magnets 53 inserted therein, a buffer plate 54 that is screwed into body member 52, and a resilient strip 55 that is interposed between plate 54 and member 52. Resilient strip 55 extends below the bottom edge of member 52 so that when the dams 25 are placed about the edges of shell 31 there is a tight vacuum seal since the resilient material, preferably silicone rubber, compensates for any irregularities in the perimeter of shell 31. Strip 55 also maintains a seal for a reservoir 56 formed by dams25 and shell 31. Plate 54 has its lower edge positioned above the lower edge of strip 55 and above the bottom of member 52 so that the edge of shell 31 can be inserted beneath it. Plate 54 has inscribed thereon an indicating mark 57 which is set at the desired thickness of the electrotype plate 32 and serves as a guide in pouring the molten lead.

-In operation, the non-printing face 33 of shell 31 is of bonding metal and then the shell is placed upon top plate 15 with printing face 28 in contact with the upper side of top plate 15 and positioned over, for example, grooves 22 and perforations 23. The heat from top plate 15 maintains the bonding layer 34 in a softened condition. Hold-down dams 25 are positioned around the edges of shell 31 with strips 55 in contact therewith to form a vacuum seal, dams 25 also forming a reservoir 56 into which molten lead is thereafter poured. Air is evacuated from the printing face 23 to hold shell 31 flat, and molten lead is poured onto the bonding layer 34 and confined within reservoir 56. The molten material is poured until it reaches the height of the indicating mark 57. After this, the lead is allowed to cool, the hold'down dams 25 are removed, the vacuum is turned off and the resulting electrotype plate 32, having a back face 36 that is perfectly parallel to printing face 28, is removed from the apparatus. By using the apparatus and following the method of this invention an electrotype plate is obtained that requires little or no shaving of the back face in order to make it fiat and parallel to the printing face.

It is to be understood that the form of the invention herein shown and described is to be taken as a preferred embodiment. Various changes may be made in the shape, size and arrangement of parts. Equivalent elements may be substituted for those described herein, parts may be reversed, and certain features of the invention may be utilized independently of the use of other features, all Without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described my invention, 1 claim:

1. Apparatus for backing up a shell having a printing face and a non-printing face to form an electrotype plate; said apparatus comprising table means composed of magnetizable material for providing a uniform supporting surface for the printing face of said shell; said surface having a groove located therein and having perforations located in said groove; vacuum means connected to said perforations for holding said shell snugly in contact with said supporting surface; and magnetic dam means firmly held on said supporting surface by magnetic attraction for holding down the edges of said shell, for forming a vacuum seal at the edges of said shell, and for forming a reservoir with the non-printing face of said shell; said groove being located within the boundary formed by said dam means.

2. The apparatus defined in claim 1, wherein said magnetic dam means includes a plurality of hold-down bars which are placed in abutting relationship around the edges of said shell, each hold-down bar being provided with a strip of resilient material positioned on the inside of said reservoir for contact with the molten material which is poured into said reservoir.

3. Apparatus for backing up a copper shell having a printing face and a non-printing face to form an electrotype plate having said printing face and a back face substantially parallel thereto, said apparatus comprising means providing a uniform supporting surface composed of magnetizable material on which the shell is placed with its printing face in flush contact with said surface, said surface having perforations located therein and positioned adjacent the surface of said shell, vacuum means connected to said perforations for evacuating air from said shell printing face for holding said shell snugly in contact with said surface, magnetic dam means firmly held on said supporting surface by magnetic attraction, said dam means being formed of elongated magnetic bars having end surfaces and side surfaces with each bar having an end surface abutting a side surface of an adjacent bar to encircle the shell, said dam means being snugly in contact with all of the edges of said shell and completely surrounding all of said edges and concurrently holding down the edges of said shell in contact with said surface, forming a vacuum seal, and forming a reservoir around and extending well above the non-printing surface of said shell.

4. The apparatus defined in claim 3, wherein said magnetic means is provided with resilient means for contacting the edges of said shell and said surface to form a tight seal.

5. Apparatus for backing up a copper shell having a printing face and a non-printing face to form an electrotype plate having said printing face and a back face substantially parallel thereto, said non-printing face being covered with a thin layer of bonding metal of low melting point, said apparatus comprising a means providing a fiat supporting magnetizable surface on top of which the shell is located with its printing face in contact with said surface, heating means adjacent said surface for maintaining said surface at a temperature above ambient for maintaining said layer of bonding metal in a softened condition, said surface having perforations located therein and positioned beneath said shell, vacuum means connected to said perforations for holding said shell in contact with said surface, and magnetic dam means on said surface in surrounding contact with all of the edges of said shell to hold said shell in contact with said surface and to form a reservoir around and above said shell, said dam means being formed of elongated magnetic bars having end surfaces and side surfaces with each bar having an end surface abutting a side surface of an adjacent bar to encircle the shell.

6. Apparatus for backing up a copper shell having a printing face and a non-printing face to form an electrotype plate having said printing face and a back face substantially parallel thereto, said shell non-printing face being covered by a layer of bonding metal in a softened condition, said apparatus comprising a top plate made of ferrous metal on which the shell is placed with its printing face in contact with the upper side of said top plate, a bottom plate connected to the lower side of said top plate, heating means positioned between said top and bottom plates for maintaining said top plate at a temperature above ambient for maintaining said bonding layer in a softened condition, said top plate having a groove located in the upper side thereof, said top plate having perforations located within said groove, the shell being positioned on said groove and perforations, a vacuum connecting conduit connected to said perforations, a plurality of hold-down dam means located on the upper side of said top plate and in contact with the edges of said shell to form a reservoir therewith to hold down the edges, and to form a vacuum seal, said groove being located within the boundary formed by said hold-down dam means each of said hold-down dams including a body member, a magnet positioned in the body member, a buffer plate attached to one side of the body member and having its lower edges spaced away from the bottom of said body member, and a strip of resilient material positioned intermediate said buffer plate and said body member and extending below the bottom of said body member and below the lower edges of said buffer plate.

References Cited in the file of this patent UNITED STATES PATENTS 1,130,066 Carter Mar. 2, 1915 1,219,289 Gounley Mar. 13, 1917 1,441,885 Sanford Jan. 9, 1923 2,074,335 Kelley Mar. 23, 1937 2,177,168 Van Bolt Oct. 24, 1939 2,182,114 Bungay Dec. 5, 1939 2,578,132 Garrett Dec. 11, 1951 2,672,664 Sudziarski Mar. 23, 1954 2,748,433 Preston et a1 June 5, 1956 

